Development of a Keratoconus-Specific Questionnaire Using Rasch Analysis
Autor: | Konrad Pesudovs, Jyoti Khadka, P Schoneveld |
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Přispěvatelé: | Khadka, Jyoti, Schoneveld, Paul G, Pesudovs, Konrad |
Rok vydání: | 2017 |
Předmět: |
Adult
Male Activities of daily living Adolescent Psychometrics Visual analogue scale keratoconus Visual Acuity patient-reported outcome Keratoconus behavioral disciplines and activities Young Adult 03 medical and health sciences 0302 clinical medicine Quality of life Rating scale Sickness Impact Profile Surveys and Questionnaires Activities of Daily Living Outcome Assessment Health Care Humans KORQ Categorical variable Keratoconus Outcomes Research Questionnaire Aged Rasch model questionnaire Construct validity activity limitation Middle Aged Ophthalmology quality of life Quality of Life 030221 ophthalmology & optometry symptoms Female Psychology 030217 neurology & neurosurgery Optometry Clinical psychology |
Zdroj: | Optometry and Vision Science. 94:395-403 |
ISSN: | 1538-9235 1040-5488 |
Popis: | Purpose: To develop and validate a keratoconus-specific quality of life (QoL) questionnaire: the Keratoconus Outcomes Research Questionnaire (KORQ). Methods: The study was carried out in three phases. Phase I: content identifications: items were identified based on an extensive literature review, open-ended patient mail survey, and expert consultations. Each item was scored on a visual analog scale (VAS). Phase II: pilot testing using Rasch analysis. Phase III: testing psychometric properties of the final version of the KORQ. Results: Phase I identified 44 items across 3 different content areas: activity limitation (26), symptoms (20), and convenience (8). The 44-item KORQ was self-administered to 158 people with keratoconus. The 44-item KORQ was multidimensional. Unidimensionality was restored by separating items across three content areas (subscales) as identified in phase I. The activity limitation and symptoms subscales demonstrated adequate measurement precision, but convenience (precision, 1.01) did not. Hence, the convenience subscale was discarded. Rasch analysis revealed that the VAS was disordered. The ordering of the VAS was restored by collapsing categories into 4. An iterative Rasch analysis guided item-removal resulted into a 29-item KORQ (18-item activity limitation and 11-item symptoms). The VAS was replaced by a discrete 4-option labeled categorical rating scale, and it was self-administered by 169 people with keratoconus. Both the subscales demonstrated good psychometric properties. The KORQ scores strongly correlated with visual acuity and contrast sensitivity demonstrating its construct validity. Conclusions: The 29-item KORQ was a psychometrically robust and valid instrument to assess the impact of keratoconus on activity limitation and symptoms. Refereed/Peer-reviewed |
Databáze: | OpenAIRE |
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